1. Technical Field
The present invention pertains to methods and apparatus for storing and dispensing liquids, particularly beverages. Specifically, the invention comprises improved methods and apparatus for pressurizing potable liquids in their containers and selectively dispensing the liquids from those containers. Although the invention has particular utility in storing and dispensing carbonated beverages such as sodas, sparkling wines, beer, etc. in a manner preventing loss of carbonation in the beverage as it is dispensed, the invention is also of value in storing and dispensing non-carbonated beverages such as juice, tea, and the like.
2. Discussion of the Prior Art
Market studies conducted on behalf of the beer and carbonated soft drink industries have indicated a consumer preference for large volume packaging for these products. For example, two liter, three liter or even larger bottles or cans have been found to be desirable to consumers. In addition, large container packaging results in lower cost per unit volume of liquid sold, thereby resulting in savings for the consumer and higher profits for the manufacturer. The problem with large containers, however, is the loss of carbonation each time the container is opened to permit a portion of its contents to be poured. This loss of carbonation in the remaining beverage, colloquially referred to as the beverage going "flat", is generally unacceptable to consumers. In this regard acceptable carbonation volume levels for wine coolers and beers are approximately 2.0 to 2.6 volumes of CO.sub.2 gas; for soft drinks and sparkling wine the acceptable range is approximately 4.0 to 5.0 volumes of dissolved CO.sub.2 gas. (Note, here, that pursuant to common industry practice, fluid pressure is determined by the volume of the fluid at a given temperature). As containers sizes increase the number of times that the container is opened and closed for dispensing typically increases, resulting in a cumulative loss of carbonation pressure. Ultimately the carbonation pressure becomes negligible whereby the remaining beverage becomes "flat" and, accordingly, its taste is not acceptable. Having experienced this waste, consumers opt for smaller single serving containers in spite of their desire to have large containers. It is therefore desirable to provide a technique for maintaining the prescribed beverage carbonation pressure in a container until all of the beverage liquid has been dispensed.
In U.S. Pat. No. 4,194,653 (Brown) there is disclosed a dispensing apparatus and technique for carbonated beverages whereby, upon removal of the original sealing cap from a container, the apparatus is placed atop the container in sealing relation. A siphon tube extends to the bottom of the container and communicates with a dispensing nozzle via a selectively actuable valve. Pressure in the headspace (i.e., the space above the liquid level) is created by carbon dioxide leaving the liquid suspension. A user of the device is instructed to shake the container to bring additional carbon dioxide out of suspension to create the necessary headspace pressure to force the beverage up through the siphon tube. However, the use of the carbonation pressure in this manner reduces the carbonation pressure in the liquid to below acceptable taste levels. In addition, the valve arrangement between the siphon tube and the dispensing nozzle is formed by a selectively movable frusto-conical valve member seated in an O-ring. Movement of the valve member from its seat causes the pressurized liquid passing through the valve to experience a rapid change to ambient pressure from the pressure in the container. The result is a "fracturing" of the carbonated liquid, causing it to vigorously foam as it is dispensed. Thus, instead of primarily liquid being dispensed into a glass or cup, the glass or cup receives mostly foam. Moreover, the foaming process removes still more carbonation from the beverage, thereby further reducing its desirability for consumption.
A similar arrangement is disclosed in U.S. Pat. No. 4,860,932 (Nagy) wherein use of escaped carbonation pressure in the headspace to dispense the liquid, and fracturing of the carbonated liquid at the dispensing valve, combine to reduce the carbonation pressure of the dispensed liquid to below acceptable levels.
It is known in the prior art to initially bottle seltzer water in, and dispense it from, a sealed container having pressurized carbon dioxide in the headspace. A siphon tube conducts the seltzer water from the bottom of the container for selective dispensing under control of a valve mounted at the top of the container. The high pressure carbon dioxide (e.g., on the order of 5.0 to 6.0 volumes of dissolved CO.sub.2) in the headspace is sufficient to dispense substantially the entire liquid contents of the container. U.S. Pat. No. 4,694,975 (Hagan) discloses a method and apparatus wherein a container is filled, shipped and sold to the consumer without the siphon and valve assembly, the latter being a separate reusable assembly adapted to be secured to the container by the consumer prior to dispensing liquid. In either case, when seltzer water is dispensed into a glass from a container using the methods and apparatus of the general type described above, the dispensed liquid experiences fracturing at the dispensing valve and loses much of its carbonation. Since seltzer water does not readily foam, the reduced pressure from fracturing may or may not suit different individual's tastes; however, for beer, cola and other flavored carbonated soft drinks, foaming and the loss of carbonation renders the beverage unacceptable for consumption.
It is desirable, therefore, to be able to dispense carbonated soft drinks, beer, and the like from the container in which it is bottled and shipped without significant loss of carbonation pressure.
Pinch point-causing turbulence in the dispensing valve noted above has adverse effects on certain non-carbonated beverages such as juices. Specifically, if certain fruit juices are agitated as dispensed by having to pass through pinch-points in the valve, they tend to froth and fill the glass or other receptacle with foam. Although large dispensing containers for juices may not be in demand for many homes, commercial establishments such as restaurants and bars have a definite need to be able to store large volumes of juices in containers from which the liquid can be easily dispensed. Under such circumstances large amounts of foam in a customer's glass becomes totally unacceptable. It is desirable, therefore, to provide a technique for dispensing beverages whereby turbulence is substantially eliminated so that the dispensed beverage, carbonated or not, has no more foam than is produced by normal pouring of liquid from a small container.
Finally, it is known in the prior art to use nitrogen to pressurize the headspace in a bottle of still wine and in cans of other non-carbonated beverages. In the wine bottle case, a stopper for the bottle is permanently connected to a canister of pressurized nitrogen and includes a siphon tube, valve and spout to permit selective dispensing of the wine. Nitrogen is preferred to air for this purpose because the oxygen in air has deleterious effects on wine. This nitrogen canister technique may have value for still wine dispensing since removal of the cork and replacing it with a stopper does not have the problem of carbonation loss that would face beer, cola, etc. In addition, the use of a separate canister to dispense soft drinks or beer is totally impractical for most consumers and is less than desirable in most commercial establishments. In the case of beverage cans, nitrogen is used to purge deleterious oxygen from the headspace during packaging and is retained in the headspace at super atmospheric pressure after sealing to prevent collapse of the can when it is stacked during shipping and storage. An example of the latter arrangement is found in U.S. Pat. No. 4,347,695 (Zobel et al). Nothing in that patent is concerned with dispensing or preserving carbonation pressure.